public class Test {
    public static void main(String[] args) {
        MyStak stak = new MyStak();
        stak.push(1);
        stak.push(2);
        stak.push(3);
        Integer a = stak.pop();
        System.out.println(a);
        Integer b = stak.peek();
        System.out.println(b);
        Integer b2 = stak.peek();
        System.out.println(b2);
        System.out.println(stak.isEmpty());
    }
}
